John MacMillan has done a magnificent reconstruction of the original 10th. I hope he will see this thread and repost his graphic. It's remarkable.
Rich -
No doubt many changes to ANGC were inevitable. For one thing, it was the only design MacK did in clay. Drainage was a problem at 10 and a couple of other holes.
That said, the original 10 was a fascinating hole. Today you rope a big hook into the catch basin valley, then hit a middle iron to a big open green. MacK's hole required a drive to the narrow ledge on the right side of the fairway if you wanted to open up a beautifully bunkered, fall-away green. It would have been a terrific short par 4.
But more generally, the history of changes to ANGC is hard to separate from the history of the rocky relationship between Cliff Roberts and Jones. From the very beginning Roberts wanted to make changes to the course that, at first, both Jones and MacK resisted and, later, that Jones resisted. But as Jones got more feeble in the late 40's and Robert's power over the club increased, Roberts found it easier and easier to implement his ideas. Many of which were hair-brained. One episode we know about, for example, are the monstrously bad changes at 8 implemented by Cliff Roberts. Jones opposed them.
Bottom line, I think it is wrong to assume that all changes to ANGC had the Jones imprimatur. Having looked at the question a bit, I now think the presumption should tilt in the other direction. Remember, Jones and Roberts weren't speaking for the last couple of decades of Jones' life and weren't getting along very all that well before they went radio silent.
It's my personal (and perhaps idiosyncratic) view that Jones poured his heart into MacK's course and, except for engineering necessities, was very reluctant to change it. Further, as Robert's gained clout and was able to impose his views (views similar to those of the USGA today, i.e., resistance to scoring is the only real measure of the worth of a design), Jones was increasingly alienated from the day-to-day decisions at ANGC until at some point he fell out of the loop altogether.
Bob